This invention relates to the novel compounds, vinyl monomers having polyenic side chains derived from highly unsaturated fatty acids and (co)polymers thereof.
Vinyl monomers having various functional groups in the side chains are known. Polymerization behavior of these monomers based on the functional groups and the relation between the structure and the properties of the resultant polymers are subjects of interest. As a particular use thereof a method for production of a polymer containing polyunsaturated acid residues is described, for example, in Japanese Published Unexamined Patent Application (KOKAI TOKKYO KOHO) No. 125497/76; graft polymerization of poly(acrylic acid) and poly(methacrylic acid) with a poly(fatty acid) through ester bonding or amide bonding was performed to test whether the graft copolymer is usable as a DDS of prostaglandin. The graft polymerization with a polymer elongated the duration of action of prostaglandin as compared with prostaglandin used alone.
The report in J. Appl. Poly. Sci., 30, 4571-4582 (1985) describes the synthesis of lauryl acrylate (LA), oleyl acrylate (OA), linoleyl acrylate (LA2), and linolenyl acrylate (LA3) from each corresponding fatty acid and the reactivity thereof. The subsequent report in J. Appl. Poly. Sci., 30, 4551-4570 (1985) describes the synthesis of the crosslinked products of the copolymers reported in the preceding paper (making use of the double bonds in the fatty acids) and the physical properties of the products. The crosslinked products were obtained more rapidly in the presence of a cobalt catalyst than in the presence of a lead catalyst, and could be obtained even without any catalyst though it took more time. Physical parameters determined included tension, glass transition temperature, and molecular weight, all of which were reported to be more desirable with copolymers with LA incapable of crosslinking. Thus the reaction of a fatty acid with a vinyl compound itself is known, but there is no report on the experiments with highly unsaturated fatty acids such as EPA and DHA. Namely no report has been published on vinyl monomers having polyenic side chains derived from highly unsaturated fatty acids and the derivatives thereof, and the polymers of said monomers, and the method for production of said monomers and polymers.
Eicosapentaenoic acid (abbreviated as EPA somewhere hereinafter) and docosahexaenoic acid (abbreviated as DHA somewhere hereinafter), contained as they are or in the form of derivatives such as glycerides in natural fat and oil, particularly in fat and oil in marine products such as mackerel, sardine, and cod, have recently become available in highly purified forms.
However, natural fat and oil including fish oil contain, in addition to EPA having 20 carbon atoms and 5 double bonds in a molecule and DHA having 22 carbon atoms and 6 double bonds in a molecule, other various fatty acids having 12 to 24 carbon atoms and 0 to 6 double bonds in each molecule abundantly. Thus, the fatty acids, usually the esters thereof, remaining as the residue in distillation may remain behind when highly purified products are to be produced from the fatty acid mixtures described above as the starting material.
It is desirable to develop a useful method for utilizing the residue in distillation, the residue which is substantially a mixture of highly unsaturated fatty acid esters.
The object of this invention is to provide novel vinyl monomers of a type unknown from the vinyl monomers developed so far. Another object of this invention is to provide polymers having double bonds in the side chains into which various functional groups can be introduced. A further object of this invention is to provide novel vinyl monomers having polyenic side chains derived from highly unsaturated fatty acids and the derivatives having double bonds in the side chains into which various functional groups can be introduced. A further object of this invention is to provide novel vinyl monomers having polyenic side chains derived from highly unsaturated fatty acids and the derivatives thereof and the polymers of said monomers. Yet another object of this invention is to provide a useful method for utilizing the fatty acid esters remaining as the residue in the distillation of esterified fish oil.
Vinyl monomers having polyenic side chains derived from highly unsaturated fatty acids represented by the general formula (1):
R1COOHxe2x80x83xe2x80x83(1) 
wherein R1 is a C19-24 hydrocarbon having 5 or 6 unsaturated bonds, and the derivatives thereof.
Highly unsaturated fatty acids represented by the general formula (1) are exemplified by eicosapentaenoic acid, docosapentaenoic acid, docosahexaenoic acid, hexadecatetraenoic acid, octatetraenoic acid, eicosatetraenoic acid, docosatetraenoic acid and/or fatty acids derived from fatty acid esters remaining as the residue in the distillation of esterified fish oil.
Derivatives of highly unsaturated fatty acids represented by the general formula (1) are exemplified by eicosapentaenol, docosapentaenol, docosahexaenol, hexadecatetraenol, octatetraenol, eicosatetraenol and/or docosatetraenol. Derivatives of highly unsaturated fatty acids used in this invention are exemplified by fatty acid esters remaining as the residue in the distillation of esterified fish oil or alcohols derived therefrom.
Vinyl monomers to bind highly unsaturated fatty acids represented by the general formula (1) or the derivatives thereof are exemplified by methacrylic acid, methacrylic acid esters, acrylic acid, acrylic acid esters, ethylene, butadiene, vinyl chloride, vinyl acetate, styrene, and acrylonitrile; that is, monomers having vinyl group that are used as starting materials for production of polymers are used.
Vinyl monomers in this invention are preferably those obtained by esterification of eicosapentaenoic acid, docosapentaenoic acid, docosahexaenoic acid and/or fatty acids derived from fatty acid esters remaining as the residue in the distillation of esterified fish oil, with 2-hydroxyethyl methacrylate. Other preferable examples are vinyl monomers obtained by esterification of eicosapentaenol, docosapentaenol, docosahexaenol and/or alcohols derived from fatty acid esters remaining as the residue in the distillation of esterified fish oil, with acrylic acid and/or methacrylic acid.
A vinyl monomer in this invention can be prepared by, e.g. reducing docosahexaenoic acid (DHA) into an alcohol either directly or through several reaction steps and reacting the alcohol with acryloyl chloride. These vinyl monomers can be polymerized by the use of various polymerization initiators. In addition the vinyl monomers can be copolymerized with other monomers.
Polymerization initiators used are preferably those known as radical polymerization initiators such as azobisisobutyronitrile (abbreviated as AIBN somewhere hereinafter), benzoyl peroxide, acetyl peroxide, etc.
Polymerization may be carried out in the solid phase (bulk polymerization) or in the liquid phase by using a reaction solvent such as chlorobenzene, dimethylformamide, or methanol.